260 fe. J. BUTLER. 



half an hour a copious zoospore formation took place. The zoo- 

 spores, without any mycelium, were washed ofi into a sterile covered 

 watch-glass and used for tlie inoculations. The material in this 

 case Avas likely to be absolutely pure, since it was obtained from an 

 aerial growth consisting exclusively of Pythium palmivorum, and 

 since some of it, used to inocidate sterile culture tubes of palmyra 

 slabs, gave no growth of foreign movdds. 



The inoculations were made on three palmyras varying from 

 6 to 12 feet in height exactly as described above, except that drops 

 of water bearing only zoospores were used. 



On the 4th day one of the trees was examined and a slight dis- 

 colouration without any depression found at the inoculated point. 

 On the 6th day all were examined and showed brownish discoloured 

 patches at the seat of inoculation, the colour being much deeper 

 than in the one examined two days earlier. A copious exudation 

 of gum was taking place from the inoculated patches. Two days 

 later all the trees showed the marginal boundary line, and two were 

 developing isolated dark brown spots on the discoloured area. By 

 the 10th day the affected area was distinctly depressed and the mar- 

 gin raised up. On this day one of the inoculated sheaths was re- 

 moved and that next below was found slightly discoloured, where 

 the parasite had reached it after penetrating through the first sheath. 

 After 4 weeks all the sheaths were removed and it was found that 3, 

 4 and 6 sheaths respectively (including that inoculated) had been 

 attacked, in the line towards the centre of the bud. In one case a 

 lateral extension of 8 inches was found on the sheath next below 

 that inoculated. 



IV. The material used was a fresh growth of mycelium bear- 

 ing ripe sporangia. It was obtained by placing pieces of a young 

 palmyra leaf- sheath, cut as aseptically as possible and with super- 

 ficial mycehum, for about 18 hours in a sterilized Petri disb. By 

 this time the previously sterile mycelium had given off numbers of 

 fertile hyphfe with sporangia ready to germinate on the addition 

 of water. 



